Distribution of the verified Middle Neolithic circular ditch systems in Europe and
the cultural groups (approx. 4850/4750-4550/4500 BC) defined on the material remains.

First compilations of all known monuments were published by Petrasch [1990] and
Trnka [1991], the latter proposed the term: mittelneolithische Kreisgrabenanlagen for this
specific type of monument. The highest density of these fascinating monuments is found
in the eastern part of Austria, mainly in the County of Lower Austria (e.g., Fig. 2 by
Neubauer [2007]). Over 40 Kreisgrabenanlagen or KGAs are known so far for the main
area of interest of this project. The monuments in eastern Austria normally are part of
large settlements and enclose a specific area of typically 0.5 to 1.2 ha. According to 14C
dating of bone material excavated from the ditches in Lower Austria, the KGAs have
been erected in the very short time span between 4850/4750–4550/4500 BC [Stadleret al.2006]. This short period seems to be valid for the other Middle European KGAs as
well.

The function of these exceptional monumental buildings which have been erected
by the early farmers with a high effort of work is still under scientific discussion. The
interpretation models include socio-cultural or socio-ritual centers [Neubauer2007, 222-236;
Podborský et al.1999],
fortifications [NemejcovŠ-PavķkovŠ1995],
market places [Stšuble2002, 307] or functions to safeguard people and their herds [Pertelwieser2001] up to
functional explanations as calendrical buildings, astronomical observatories or solar temples
[Weber1986;
Becker1996; Bertemes and Schlosser2004; Zotti2008; Schier2008].
After the initial very contrary discussion phase there is a trend obvious towards multifunctional
interpretation models [Neugebauer-Maresch 1995, 87;
Stšuble 2007, 180;
Neubauer 2007,217-236;
Petrasch 2001]. As the monuments were not erected in strategic positions and
because they have many regular oriented entrances the interpretation as fortification seems
unlikely [Trnka 1991, 317]. As well we do not think that they represent emphasized
settlement areas as there are no indications of buildings inside the monuments beside the
palisades or single posts. The ditches and palisades form an enclosure, their perimeters
separate the outside from the inside. The narrow entrances strictly control the access to the
interior mainly invisible from the outside [Gibson 2005]. This element of limited access
seems not to be based on fortification reasons but could be based on ritual activities
[Stšuble 2007;
Neubauer 2007;
Gibson 2005] to be seen in a social context of the early farmer societies.

1.2 Astronomical aspects of Kreisgrabenanlagen

Contrary to the much younger megalithic monuments like Stonehenge
[Hawkins 1973;
Thom 1967;
Thom and Thom 1978],
the continental wooden KGAs are not preserved in the landscape. As
soon as the first maps were available the KGAs became subject of archaeoastronomical
considerations. The main interest was set on the orientation of the entrances
[Weber1986; Becker1996; Karlovský1999; Karlovský and Pavķk2002]. Ritual sky
observations have been proposed most notably by Becker [1996], who based his analysis on
magnetograms that indicated that the entrances of the Bavarian KGAs are oriented towards rising
or setting points of the Sun at the solstices.

In preparation of a large County exhibition on Kreisgrabenanlagen in 2005 [Daim and
Neubauer2005], the theory of astronomical aspects has also been investigated for the
KGAs of Lower Austria [Zottiforthcoming, 2005, 2008; Kastowskiet al.2005]. This
preliminary research was based on the results of a systematic archaeological prospection
combining field surveys, aerial archaeology and magnetic prospection [Neubauer2007]. Our
approach was different from the theoretical considerations so far as we based our studies
on archaeological interpretation maps and reconstructions based on magnetic modeling
of the magnetic surveys [Eder-Hinterleitner and Neubauer2001] combined with
the digital terrain models derived from aerial archaeology [Neubauer2001; Doneuset al.2005]. Therefore it became possible to include the horizon and to derive virtual
reality models of the monuments [Gervautz and Neubauer2005]. These models formed
the input for astronomical simulation software which made it possible to explore the
astronomical aspects and the constraints in the reconstructed virtual Middle Neolithic scenery
[Zotti2008].

According to these first investigations on selected monuments from Lower Austria, solar
alignments of entrances could be verified for several KGAs even with a higher degree of detail and
reliability than the previous approaches. A first — preliminary — investigation into stellar
alignments revealed promising indications on the possible observation of distinct bright stars as well.
Our preliminary work promises remarkable future results towards the astronomical aspects of the
KGAs by a thorough archaeoastronomical analysis based on comparable data of the monuments.
This comparable and comprehensive data base exists so far only for the KGAs of Lower
Austria and is based on a preliminary research project investigating all known KGAs. The
resulting digital archive provides georeferenced aerial and magnetic prospection data, digital
terrain models, archaeological interpretation maps and excavation results [Neubauer and Melichar2005].